Microscopic examination of tissue samples, particularly those obtained by biopsy, is a common method for diagnosis of disease. In particular, immunohistochemistry (IHC), a technique in which specific antibodies are used to detect expression of specific proteins in the tissue sample, is a valuable tool for diagnosis, particularly for the detection and diagnosis of cancer.
Uroplakins (“UP” or “Ups”) comprise a group of 4 transmembrane proteins (UPs Ia, Ib, II, and III) expressed in the luminal surface of normal urothelial superficial (umbrella) cells, which are specific differentiation products of urothelial cells. Uroplakin II (“UP II”) may be a 15 kDa protein component of the urothelial plaques which may enhance the permeability barrier of the urothelium. The expression of UP II may be aberrant in urinary bladder transitional cell carcinoma (“TCC”) of the bladder and thus may make it a useful marker for the diagnosis of cancer. The Wu et al. reference includes discussion of UP II mRNA as a promising diagnostic marker for bladder cancer and perhaps even micrometastases of bladder cancer in the pelvic lymph nodes (see article, “Uroplakin II as a promising marker for molecular diagnosis of nodal metastases from bladder cancer: comparison with cytokeratin 20.” Wu X, Kakehi Y, Zeng Y, Taoka R, Tsunemori H, Inui M. J Urol. 2005 December; 174(6):2138-42, hereby incorporated by reference herein.) UP II mRNA was detected in 19 of 19 (100%) and 15 of 16 (93.8%) bladder tumor tissue specimens and pelvic lymph node samples with metastasis, respectively. On the other hand, UP II mRNA was detected in only 6 cases out of 66 (10%) pelvic lymph node samples without metastasis. Therefore, positive expression of UP II mRNA may indicate nodal metastases from bladder cancer. It may be important to determine the nodal metastases in patients with bladder cancer after radical cystectomy as this subpopulation of patients may urgently need postoperative chemotherapy to survive. The authors conclude that the detection of UP II mRNA may improve clinical outcome following radical cystectomy perhaps by providing helpful information in the diagnosis and management of TCC. It is desirable, therefore, for development of an anti-UP II antibody for detection of UP-II protein expression in the tissues of patients such as with TCC or the like.
Studies have shown UP II mRNA to be expressed in bladder tissues and peripheral blood of patients with primary and metastatic TCCs, perhaps suggesting its potential role as a biomarker for urothelial carcinomas. The clinical usefulness of UP II may have been recognized from these studies perhaps solely based on its mRNA data. Additional investigations characterizing the protein localization of UPII in TCC may be warranted, especially when the protein molecules may be more stable than mRNA molecules. One study employed a pan-UP antibody which may have reacted with all UPIb, UPII, and even UPIII isoforms perhaps to demonstrate the persistent expression of UP in advanced urothelial carcinomas; however, the specific UP II protein level could not be determined using this pan-UP antibody. (See, Persistent Uroplakin Expression in Advanced Urothelial Carcinomas: Implications in Urothelial Tumor Progression and Clinical Outcome. Hong-Ying Huang, Shahrokh F. Shariat, Tung-Tien Sun, Herbert Lepor, Ellen Shapiro, Jer-Tsong Hsieh, Raheela Ashfaq, Yair Lotan, and Xue-Ru Wu, Hum Pathol. 2007 November; 38(11): 1703-1713, hereby incorporated by reference herein). Little may be known about the protein expression of UP II in urothelial cancer, possibly due to the absence of a specific anti-UP II antibody.
A clear need exists for a sensitive and even specific anti-Uroplakin II antibody for use in cancer diagnosis. Anti-UP III antibodies have been previously developed as markers for carcinoma of urothelial origin. Here the present invention provides an anti-UP II antibody [clone BC21] which may be highly specific and may even be more sensitive than the anti-UP III antibody [clone BC17]. In cases of TCC, an example of the present invention provides an anti-UP II antibody that exhibited an increased sensitivity (about 46/59, about 78%) compared to the anti-UP III antibody (about 33/59, about 56%). Perhaps in addition to its stronger staining profile, the anti-UP II antibody [BC21] may exhibit a wider localization pattern compared to anti-UP III antibody. This could be due to the superior sensitivity of the anti-UP II antibody or perhaps even the two isoforms may have distinct roles in the formation of urothelial plaques. The difference in their function may not be fully known; however, mice lacking the UP II gene showed no urothelial plaque formation while mice lacking the UP III gene may still retain small urothelial plaques. If UP II and UP III indeed exhibit non-overlapping functions, determination of either isoform may not be sufficient for an effective diagnosis of TCC. Therefore, an anti-UP II antibody may be needed for a more complete coverage of protein expression of UP isoforms.
The development of an anti-UP II antibody may aid in the diagnosis of primary and even metastatic TCCs, may aid in the verification of UP II mRNA expression perhaps in previous clinical studies, and may even aid in distinguishing a protein expression of UP II versus UP III. New anti-Uroplakin II antibodies such as anti-Uroplakin II antibody [BC21] with perhaps increased staining sensitivity, and perhaps even while preserving equal or even superior staining specificity such as compared to anti-Uroplakin III antibody [BC17], have been provided in the present invention.